Owing to advantages such as high working voltage, long cycle service life, no memory effect, little self-discharge, being environmentally friendly and the like, lithium-ion battery has been widely applied in portable electronic products and electric vehicles. At present, commercial lithium-ion battery is mainly made of graphite-type anode materials. However, the theoretical specific capacity thereof is only 372 mAh/g, and cannot meet the requirements of future lithium-ion battery on high-energy density. It is reported at home and abroad that metal elements, metal oxides and metal alloy compounds capable of forming alloys with lithium, such as Si, Sn, Ge, Pb, SiO, SnO, SbSn, Mg2Si and the like, have higher specific capacity. However, the battery capacity of these materials decreases rapidly during the use. Thus, the actual applications thereof are limited to a certain extent.
It is deemed by analyses that large expansion and contraction of the volume result in material damage and crushing during delithiation and lithiation of metal elements, alloys and metal oxides materials for anodes, which is the main cause for rapid decrease of the material capacity. Thus it has an important meaning for increasing the cycling stability of alloys and metal oxides materials for anodes to inhibit the volume expansion of the materials and to increase the structural stability of the materials. Currently, the volume expansion of the materials is improved primarily by nanocrystallization, alloying and multi-composition (or composing with active or non-active materials).
CN103199223A discloses a Cu—Cr—Si ternary anode material, and a process for preparing the same. It discloses mixing copper powder, chromium powder and silicon powder and calcining to prepare alloy ingots, then pulverizing to obtain Cu—Cr—Si ternary alloy powder having a micron size or less. The resultant materials have a higher capacity and a better cycling performance. However, the continuous phase formed by silicon and chromium in the ternary material prepared by such process still has a large size, and does not homogeneously disperse copper, chromium and silicon. CN103560249A discloses a multi-composite anode material and a process for preparing the same, comprising adding silicon powder, carbon nano-tube, expanded graphite into a polyvinyl alcohol or polyethylene glycol water system, then stirring-drying and calcining to obtain a multi-composite material consisting of nano-silicon powder, carbon nano-tube, expanded graphite and amorphous carbon. Such composite material has a better electroconductivity and a high capacity. However, nano-silicon powder is hard to be sufficiently dispersed during the preparation, so as to result in a lower initial charge-discharge efficiency of such material.
Therefore, it is a technical challenge in the lithium-ion battery field to develop a multi-composite anode material having a high electroconductivity, a high capacity, a high initial charge-discharge efficiency and a better cycling stability.